1. Field of the Invention
The present invention relates to a transfer apparatus, in particular to a transfer apparatus designed to carry a thin plate-like work such as a substrate along a straight path.
2. Description of the Related Art
Among conventional transfer apparatuses, there is a type which has a mechanism for moving their hands along a straight path (linear movement mechanism). These robots are simpler in construction and less expensive than so called multi-joint robots, and used widely in e.g. manufacturing processes of semiconductor devices and liquid crystal display panels, for moving thin plate-like works such as wafers and glass substrates into and out of different process chambers.
Such a transfer apparatus for carrying a thin plate-like work is disclosed in JP-A-2005-125479, for example. The conventional transfer apparatus includes link arm mechanisms supported by a swivel. The link arm mechanisms have their end portions provided with a hand which is capable of holding a plate-like work such as a substrate horizontally. The swivel is supported rotatably with respect to a stationary base. As the swivel turns about a vertical swivel axis on the stationary base, the link arm mechanisms are rotated therewith. The stationary base incorporates therein a drive source for driving the link arm mechanisms, and a transmission shaft extending into the swivel to transmit power from the drive source to the link arm mechanisms. As the driving power is transmitted from the drive source in the stationary base via the transmission shaft, the link arm mechanisms are actuated and as the link arm mechanisms are actuated, the plate-like work held by the hands are moved linearly in a horizontal plane, whereby the plate-like works are moved from a predetermined location to another location. The swivel also supports guide members. To the guide members, guide rails are fixed so as to support and guide the hands when they are moved in a predetermined direction as the link arm mechanisms swing open and close. This arrangement enables to move the hands with the plate-like works more stably along the linear path.
Meanwhile, a recent trend in the manufacture of liquid crystal display panels, for example, is to increase the panel size. This leads to a requirement for increase in the size of the hands in the transfer apparatus, increase in the size of the work to be transported thereby, and as a result, increase in the distance of the transport path.
However, as the travel stroke increases with the increasing size of the work, the overall size of a transfer apparatus also have to increase. Because of such size increase, the handling of a transfer apparatus at the time of installing, for example, tends to be difficult.